Fix a 64-bit pointer truncation bug found by VC++ 2015

webrtc/base/trace_event.h

Index: webrtc/base/trace_event.h
diff --git a/webrtc/base/trace_event.h b/webrtc/base/trace_event.h
index c14cbff03077450e005c81efa443d0db70b3ee88..3916af4fb61bf713139f60f617c02793b24ade3e 100644
--- a/webrtc/base/trace_event.h
+++ b/webrtc/base/trace_event.h
@@ -701,7 +701,7 @@ class TraceID {
 
   explicit TraceID(const void* id, unsigned char* flags)
       : data_(static_cast<unsigned long long>(
-              reinterpret_cast<unsigned long>(id))) {
+              reinterpret_cast<uintptr_t>(id))) {
     *flags |= TRACE_EVENT_FLAG_MANGLE_ID;
   }
   explicit TraceID(ForceMangle id, unsigned char* flags) : data_(id.data()) {